package org.apache.solr.search.grouping.collector;

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.Collector;
import org.apache.lucene.search.Scorer;
import org.apache.solr.search.DocSet;

import java.io.IOException;

/**
 * A collector that filters incoming doc ids that are not in the filter.
 * 
 * @lucene.experimental
 */
public class FilterCollector extends Collector {

	private final DocSet filter;
	private final Collector delegate;
	private int docBase;
	private int matches;

	public FilterCollector(DocSet filter, Collector delegate)
			throws IOException {
		this.filter = filter;
		this.delegate = delegate;
	}

	public void setScorer(Scorer scorer) throws IOException {
		delegate.setScorer(scorer);
	}

	public void collect(int doc) throws IOException {
		matches++;
		if (filter.exists(doc + docBase)) {
			delegate.collect(doc);
		}
	}

	public void setNextReader(IndexReader indexReader, int docBase)
			throws IOException {
		this.docBase = docBase;
		delegate.setNextReader(indexReader, docBase);
	}

	public boolean acceptsDocsOutOfOrder() {
		return delegate.acceptsDocsOutOfOrder();
	}

	public int getMatches() {
		return matches;
	}

	/**
	 * Returns the delegate collector
	 * 
	 * @return the delegate collector
	 */
	public Collector getDelegate() {
		return delegate;
	}
}
